title: Identification and mRNA expression of antioxidant enzyme genes associated with the oxidative stress response in the Wuchang bream (Megalobrama amblycephala Yih) in response to acute nitrite exposure.
abstract: Aquatic organisms possess cellular detoxification systems to deal with pollutants. To explore the influence of reactive oxygen species (ROS) generated in response to nitrite on oxidative stress defenses and the antioxidant system in Megalobrama amblycephala, the full length cDNA sequences were determined for three antioxidant-related genes, namely catalase (MaCAT), selenium-dependent glutathione peroxidase (MaGPx1) and Cu/Zn superoxide dismutase (MaCu/Zn-SOD). Encoded polypeptides that exhibited high identity and similarity with corresponding proteins in other fish species. Expression levels of these antioxidant genes were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) technique. MaCAT, MaGPx1 and MaCu/Zn-SOD expression was greatest in the liver and qRT-PCR was used to assess expression of these genes in juvenile fish during 72 h of exposure to 15 mg/L nitrite. Prolonged nitrite exposure resulted in the formation of excess ROS that caused oxidative damage to lipids and proteins and reduced the activities of antioxidant enzymes. Fish exposed to nitrite also showed liver damage. This study provides transcriptional data for MaCAT, MaGPx1 and MaCu/Zn-SOD that suggest expression is related positively with oxidative stress induced by nitrite exposure, indicating that imbalance between ROS and antioxidant defenses is one mechanism underlying nitrite toxicity in M. amblycephala.
authors.affiliation: Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, PR China.
authors.forename: Shengming
authors.initials: S
authors.lastname: Sun
authors.forename: Xianping
authors.initials: X
authors.lastname: Ge
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
authors.forename: Fujun
authors.initials: F
authors.lastname: Xuan
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D003530:Cyprinidae / Q000235:genetics* / Q000378:metabolism; D005979:Glutathione Peroxidase; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008969:Molecular Sequence Data; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D017385:Sequence Homology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; D009573:Nitrites; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase
keywords: Gene expression; Liver; Megalobrama amblycephala; Nitrite; Oxidative stress